| 3 | ÷ | d | = | 1 | ÷ | ( | d | + | 1 | ) | + | 1 | ÷ | ( | d | + | 3 | ) |
| 方程两边同时乘以: | d | , | ( | d | + | 1 | ) |
| 3 | ( | d | + | 1 | ) | = | 1 | d | + | 1 | ÷ | ( | d | + | 3 | ) | × | d | ( | d | + | 1 | ) |
| 3 | d | + | 3 | × | 1 | = | 1 | d | + | 1 | ÷ | ( | d | + | 3 | ) | × | d | ( | d | + | 1 | ) |
| 3 | d | + | 3 | × | 1 | = | 1 | d | + | 1 | ÷ | ( | d | + | 3 | ) | × | d | d | + | 1 | ÷ | ( | d | + | 3 | ) | × | d | × | 1 |
| 3 | d | + | 3 | = | 1 | d | + | 1 | ÷ | ( | d | + | 3 | ) | × | d | d | + | 1 | ÷ | ( | d | + | 3 | ) | × | d |
| 方程两边同时乘以: | ( | d | + | 3 | ) |
| 3 | d | ( | d | + | 3 | ) | + | 3 | ( | d | + | 3 | ) | = | 1 | d | ( | d | + | 3 | ) | + | 1 | d | d | + | 1 | d |
| 3 | d | d | + | 3 | d | × | 3 | + | 3 | ( | d | + | 3 | ) | = | 1 | d | ( | d | + | 3 | ) | + | 1 | d | d | + | 1 | d |
| 3 | d | d | + | 3 | d | × | 3 | + | 3 | ( | d | + | 3 | ) | = | 1 | d | d | + | 1 | d | × | 3 | + | 1 | d | d | + | 1 | d |
| 3 | d | d | + | 9 | d | + | 3 | ( | d | + | 3 | ) | = | 1 | d | d | + | 3 | d | + | 1 | d | d | + | 1 | d |
| 3 | d | d | + | 9 | d | + | 3 | ( | d | + | 3 | ) | = | 1 | d | d | + | 4 | d | + | 1 | d | d |
| 3 | d | d | + | 9 | d | + | 3 | d | + | 3 | × | 3 | = | 1 | d | d | + | 4 | d | + | 1 | d | d |
| 3 | d | d | + | 9 | d | + | 3 | d | + | 9 | = | 1 | d | d | + | 4 | d | + | 1 | d | d |
| 3 | d | d | + | 12 | d | + | 9 | = | 1 | d | d | + | 4 | d | + | 1 | d | d |